Prior art paint sprayers include a cup gun 1 of the type shown in FIG. 1 (taken from U.S. Pat. No. 4,160,525, the entire contents of which are expressly incorporated by reference herein) wherein the paint 3 was held in a reservoir 4 attached to the gun 1. In such devices, paint was drawn from the reservoir or paint cup 4 via a siphon tube 5 (shown in chain lines) into a cylinder or chamber 6 and compressed by a piston rod 7 reciprocating in the cylinder to deliver the paint to a small orifice in a spray tip 8 where it was atomized as it left the gun. A paint return port 9 allows paint that leaks past the piston rod to return to the paint cup 4.
Another prior art U.S. Pat. No. 5,248,089, illustrates a sprayer with a separate paint reservoir, where the paint gun is a conventional cup gun, except with an extended suction set to draw paint from a backpack reservoir. As used herein, “paint” is understood to refer to conventional latex and oil-based paints, as well as other similar coatings, such as, but not limited to stains (with or without opaque pigment), lacquers, varnishes, clear polymer coatings and the like.